1000 times this.
If you really don't care about the license, just use MIT. It has the best combination of simplicity, compatibility with every other license, and it's already known and used in just about every collection of any sizeable amount of free or proprietary software.
Trying to go even further by using a weird, probably not legally enforceable declaration like this one, or other oddball things like public domain dedications, the Unlicense, the WTFPL, or CC0 is just likely to lead to more confusion, more problems with legal ambiguities in different jurisdictions, simply more time spent reading and evaluating the licenses to make sure there's nothing hidden or that it does have legal meaning in your jurisdiction, etc.
Yes, there are a few prominent examples of public domain dedication that are widely used, like SQLite. They make it work out by actually having all contributors sign an affidavit, and additionally charging a fee for people who really do want or need a license rather than the public domain dedication. Thus, being public domain is actually more work and more friction for the project than if everyone just licensed their contributions under a permissive license like MIT.